STATEMENTS OF CASH FLOWS (Unaudited) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017
CASH FLOWS FROM OPERATING ACTIVITIES
Net loss	$ (9,278)	$ (9,975)
Adjustments to reconcile net loss to net cash used in operating activities:
Gain on investments	(44)	(20)
Amortization of discounts on investments		11
Depreciation and amortization	332	273
Stock-based compensation	3,090	2,818
Loss on sale of equipment	15
Loss on early extinguishment of debt	10
(Gain) loss on remeasurement of common stock warrant liability	1	(65)
(Increase) decrease in current assets:
Accounts receivable	(36)	3
Prepaid expenses	(166)	165
Inventory	(578)	(337)
Deposits	7	(8)
Increase (decrease) in current liabilities:
Accounts payable	(185)	(176)
Accrued contract cancellation settlement		(1,000)
Accrued expenses	(66)	703
Deferred rent	(18)	12
Net cash used in operating activities	(6,916)	(7,596)
CASH FLOWS FROM INVESTING ACTIVITIES
Purchase of securities		(2,940)
Proceeds received on sale of securities	2,619
Proceeds received on sale of equipment	185
Purchase of property and equipment	(212)	(885)
Net cash provided by (used in) investing activities	2,592	(3,825)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from the issuance of common stock, net	5,132
Proceeds from the issuance of notes payable	9	437
Repayments of notes payable, net	(236)	(48)
Repayments of notes payable, related parties	(12)	(18)
Repayments of capital lease obligations	(50)	(77)
Proceeds from the exercise of warrants	2,213
Payment of employee withholding taxes relating to share-based awards	(42)
Net cash provided by financing activities	7,014	294
NET CHANGE IN CASH	2,690	(11,127)
CASH AT BEGINNING OF PERIOD	2,101	11,826
CASH AT END OF PERIOD	4,791	699
SUPPLEMENTAL INFORMATION:
Interest paid	60	55
Income taxes paid
NON-CASH INVESTING AND FINANCING ACTIVITIES:
Deemed dividend	333
Purchases of equipment under capital lease obligations	$ 37	$ 316